Proliferative diseases, such as for example, cancer, represent a tremendous burden to the health-care system. Cancer, which is typically characterized by the uncontrolled division of a population of cells frequently results in the formation of a solid or semi-solid tumor, as well as subsequent metastases to one or more sites. In addition to surgery, conventional methods of cancer treatment include radiotherapy, which operates to effectuate physical damage to malignant cells so as to render them incapable of cell division, and/or chemotherapy, which generally involves systemically administering cytotoxic chemotherapeutic drugs that alter the normal structure, function or replication of DNA.
However, a problem with these approaches is that radiation in the case of radiotherapy, and chemotherapeutic drugs in the case of chemotherapy, are also toxic to normal tissues, and often create life-threatening side effects.
A very promising therapeutic approach which may be applied either alone or in combination with radiotherapy and/or chemotherapy in the treatment of cancer is hyperthermia, as indicated by recent clinical trials (M. H. Falk, R. D. Issel, “Hyperthermia in oncology”, Int. J. Hyperthermia 17: 1-18 (2001); P. Wust, B. Hildebrandt, G. Sreenivasa, B. Rau, J. Gellermann, H. Riess, R. Felix.
P. Schlag, “Hyperthermia in combined treatment of cancer”, The Lancet Oncology, 3: 487-497 (2002); A. Jordan, T. Rheinlander, et al. “Increase of the specific absorption rate (SAR) by magnetic fractionation of magnetic fluids”, Journal of Nanoparticle Research 5 (5-6): 597-600 (2003); A. Jordan, W. Schmidt et al., “A new model of thermal inactivation and its application to clonogenic survival data for human colonic adenocarcinoma cells”, Radiation Research 154(5): 600-607 (2000); A. Jordan, R Schlolz, et al., “Presentation of a new magnetic field therapy system for the treatment of human solid tumors with magnetic fluid hyperthermia”, Journal of Magnetism and Magnetic Materials 225(1-2): 118-126 (2001).
Hyperthermia may be defined as a therapeutic procedure used to increase temperature of organs or tissues affected by cancer between 41 to 46° C. in order to induce apoptosis of cancer cells.
Hyperthermia, when used in combination with radiotherapy, is known to enhance radiation injury of tumor cells, and when used in combination with chemotherapy, is known to enhance chemotherapeutic efficacy.
Further, even mildly elevated temperatures are known to significantly potentiate the effects of radiotherapy and chemotherapy.
Such combinations of treatment modalities could result in lower doses of chemotherapeutic agents or radioactivity necessary to achieve a given effect, thus resulting in less toxicity.
Therefore, using hyperthermia should be considered as an advantageous treatment modality allowing to reduce life-threatening side effects caused by radiotherapy and chemotherapy.
Amongst the various techniques proposed for achieving the required temperature increase, it may be cited for example those reported in details by P. Wust, B. Hildebrandt, G. Sreenivasa, B. Rau, J. Gellermann, H. Riess, R. Felix, P. Schlag, “Hyperthermia in combined treatment of cancer” in The Lancet Oncology, 3: 487-497 (2002) and by P. Moroz, S. K. Jones and Bruce N. Gray, “Status of Hyperthermia in the Treatment of Advanced Liver Cancer”, in J. Surg. Oncol. 77: 259-269 (2001).
However, these various techniques used so far to induce hyperthermia still suffer from significant limitations, the most important of which being a poor control of the heat delivered to the tumor, a poor control of the intratumoral space filling, and a poor control of the precise localization of the hyperthermic effect.
Therefore, providing a hyperthermia technique to reach a controlled temperature at moderate temperatures in a defined tumor target site is a technical challenge still under development.
Some methods for inducing a localized and targeted hyperthermia by using heat-generating nanoparticles have been proposed.
WO 01-58458 proposes a method for inducing a localized and targeted hyperthermia in a cell or tissue by delivering nanoparticles of the nanoshell type having a discrete dielectric or semiconducting core section of silica doped with rare earth emitter, or gold sulfide, surrounded by a metal conducting shell layer of gold, to said cell or tissue and exposing said nanoparticles to electromagnetic radiation under conditions wherein said nanoparticles emit heat upon exposure to said electromagnetic radiation. The core and the shell constituting the nanoparticle may be linked by using biodegradable materials such as a polyhydroxy acid polymer which degrades hydrolytically in the body, in order to facilitate the removal of the particles after a period of time.
WO 03-055469 discloses a method for inducing a localized and targeted hyperthermia by incorporating into tumor cells, through ionic targeting, nanoparticles of the shell type, having a superparamagnetic core containing iron oxide and at least two shells surrounding said core, more particularly a cationic inner shell and an anionic outer shell, and exposing said nanoparticles to electromagnetic radiation under conditions wherein said nanoparticles emit heat upon exposure to said electromagnetic radiation.
U.S. Pat. No. 6,514,481 proposes the so-called “nanoclinics” that consist in iron oxide nanoparticles in a silica shell and surrounded by a targeting agent, and optionally containing a tracking dye. Application of a constant magnetic field is thought to destroy targeted cells through a magnetically induced lysis—in contrast to the heat generation obtained under an alternative magnetic field.
U.S. Pat. No. 6,541,039 by A. Jordan and coworkers also proposes iron oxide particles, embedded in at least two shells. The outer shell having neutral and/or anionic groups allows an appropriate distribution into the tumoral tissue. The inner shell displays cationic groups to promote adsorption/absorption by the cells. The nanoparticles are injected as a suspension (“magnetic fluid”) and subsequently exposed to an alternative magnetic field for hyperthermic treatment.
However, these methods do not allow the tissue to reach a controlled temperature at moderate temperatures in a defined target volume and to repeat the heating procedure in the defined target volume without repeated administration of the formulation containing nanoparticles.
JP 10-328314 discloses a shaped material implant which is invasively implanted in a bone for hyperthermia treatment, said shaped material implant comprising an alumina powder, magnetite powder having a diameter over 50 nm which is capable of generating heat in an alternating magnetic field, and a polymerized methacrylate monomer.
U.S. Pat. No. 7,918,883 discloses a magnetically heated article which employs an externally applied high frequency magnetic field in conjunction with two grades of magnetically susceptible nanomaterials having different Curie temperatures (TC1, TC2) to limit the upper temperatures to which the article will be heated upon application of an alternating magnetic field. The Curie temperature (Tc), or Curie point, is the temperature at which a ferromagnetic or a ferrimagnetic material becomes paramagnetic on heating; the effect is reversible. Upon subjecting the nanoparticles to an alternating magnetic field, self-limiting induction heating occurs as a result of magnetic hysteresis losses which ceases when the temperature of the nanoparticles reach their respective Curie temperatures.
In a disclosed application, a self-expanding Nitinol stent is heated to effect either one-way or two-way shape memory changes in the stent configuration. In an alternate application, heating to the first Curie temperature is employed to effect a one-way shape memory expansion and when the stent has deployed, further heating to the second Curie temperature is used to deliver a therapeutic agent through thermal release from a carrier. In a further alternate application, a material having an appropriate Curie temperature may be used to achieve local temperatures sufficient to inhibit restenosis by heating the cells proximate the stent to induce cell apoptosis; however the stent does not continue to heat beyond the Curie temperature which might otherwise damage the wall of vessel. In this application, the stent may be periodically reheated in situ to inhibit recurring restenosis without invasive treatment.
Barati et al. (“Extraordinary induction heating effect near the first order Curie transition”, Appl. Physics Letters 105, 162412 (2014)) discloses a material having the composition LaFe11.57Si1.43H1.75 and a TC of 319 K (45.85° C.), which is in the range (315 to 319 K) appropriate for hyperthermia treatment of cancerous cells. Barati further discloses that the Curie temperature may be tuned between 204 K and 350 K by altering the degree of hydrogen incorporation. In addition, Barati discloses that the family of compositions undergoes a dramatic increase in hysteresis loss near TC which has been attributed to phase coexistence in which the ferromagnetic phase is induced by a magnetic field in a matrix of the paramagnetic phase resulting in an enhanced loss power from 10±0.6 kJm−3 at 315 K to 80±5.7 kJm−3 at 317.7 K. Their analysis showed that the energy loss of the LaFe11.57Si1.43H1.75 compound is highly dependent on the temperature and the expected power loss is maximized just below TC followed by immediate attenuation of the heating effect at TC. A similar increase in the induction heating effect immediately below TC is expected for rotational relaxation processes in magnetic fluids.
The Specific Absorption Rate (SAR) is a useful comparative measure of the rate at which power is absorbed per mass in these processes and usually has units of watts per kilogram (W/kg) when applied to absorption of a radio frequency (RF) electromagnetic field by the human body. SAR varies as a function of frequency (kHz) and the magnetic field intensity (H). The SAR for LaFe11.57Si1.43H1.75 has been reported as 522 W/g at 279 kHz and 8.8 kA/m, while more conventional materials such FeO have been reported to exhibit a SAR of 15 (ferromagnetic) to 89 (superparamagnetic) W/g under those conditions. Similarly high SAR values are expected for LaFe11.57Si1.43Hx over the range 0<x≤2.27.
While the high SAR and appropriate TC of the LaFe11.57Si1.43Hx materials make them attractive as agents for magnetic field induced hyperthermia treatment of selected cells, the narrow temperature range (˜3° C.) associated with the observed SAR enhancement and the need to raise core tissue temperatures by about 4 to 8° C. requires a combination of longer exposure times, higher fields, and/or higher frequencies than would otherwise be desirable.